1. Field of the Invention
The present invention relates to an apparatus for cleaning and more particularly to an apparatus for cleaning cylindrical, elongate members such as nuclear reactor vessel studs.
2. Description of the Prior Art
A conventional nuclear reactor vessel is closed on the top by a member known as a reactor vessel head. During operation, the pressure vessel head is secured to the pressure vessel in a pressure tight manner. This is commonly accomplished by the use of a plurality of studs which are spaced about the circumference of a flange formed where the pressure vessel and pressure vessel head are joined.
During refueling and maintenance operations, the reactor pressure vessel head is routinely removed from the pressure vessel. Prior to reassembly, the studs used to join the heads to the vessels are cleaned for ease of reassembly and for non-destructive testing. In addition, a lubricant is used on the studs to facilitate reassembly. After removal, it is desirable that the old lubricant as well as any accumulated dirt and crud be removed so that the stud can be cleanly relubricated prior to its reuse.
To date, no adequate device for cleaning such studs has been developed.
Ransonoff, in U.S. Pat. No. 2,632,980 discloses a method and apparatus for wet grit blasting of a liquid containing suspended grit particles. The liquid is blasted against an article to be cleaned. A centrifugal type pump is used to form a liquid-grit suspension. The suspension is then sprayed from a projector nozzle at workpieces which may continuously advance through the grit blast on a rotating table or be batch tumbled in a rotary mill. Alternatively, the nozzle may be advanced relative to a stationary workpiece.
Nolan, in U.S. Pat. No. 3,103,765 discloses a slurry blasting device wherein the workpiece and the blast gun are manually manipulatable. The device also includes an exhaust system which returns airborne abrasive particles to a slurry hopper for reuse.
Richter, in U.S. Pat. No. 3,685,208 discloses a device for directing a high pressure jet against an advancing array of oscillating workpieces from above and below. A recovery system is employed to recapture the sprayed medium.
Kosar, in U.S. Pat. No. 3,242,618 teaches a method for blasting and flush off with treatment of a large number of small manufactured parts without clamping or the like by tumbling the parts in a perforated drum, thus exposing all surfaces of the parts to processing.
Burack et al., in U.S. Pat. No. 4,219,976 disclose a machine and method for decontaminating a nuclear steam generator channel with an assembly that is adapted to be positioned in the channel head and to sweep a blaster nozzle along an associated track in the head to decontaminate the area in the vicinity of the track.
Umbricht et al, in U.S. Pat. No. 3,150,460 discloses a nozzle structure for blasting grit at the surface of an article to be cleaned.
Other systems for spraying abrasives, some of which teach various recovery systems, are disclosed in U.S. Pat. Nos. 4,333,275; 4,330,968; 4,319,435; 3,455,062; 3,237,351 and 2,667,014.
None of the systems discussed above teach the use of a stud cleaning apparatus wherein the studs cleaned are rotated while a spray nozzle traverses the length of the stud spraying a mixture of high pressure water and abrasive particles at the stud for cleaning and decontamination purposes.